Process method about the service connection between the wireless local area network and user terminal

ABSTRACT

A method for processing a service connection between a user terminal and a Wireless Local Area Network (WLAN) is provided. A WLAN interactive network includes at least a WLAN user terminal, a WLAN access unit, a service control unit and a user information storage unit. The method includes setting flags that represent the attached or detached status of the service connection between the user terminal and the WLAN in the WLAN user terminal and the service control unit respectively; and establishing or canceling the connection between the user terminal and the network through the interaction between the WLAN user terminal and the WLAN, meanwhile modifying the corresponding flags.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/869,622, filed on Oct. 9, 2007, which is a continuation of U.S.patent application Ser. No. 11/146,288, now U.S. Pat. No. 7,298,726,filed on Jun. 6, 2005. The application Ser. No. 11/146,288 is acontinuation of International Application No. PCT/CN03/00921, filed onOct. 30, 2003. The International Application claims the benefit ofpriority from Chinese Patent Applications No. CN02154432.8, filed onDec. 12, 2002. The Chinese Patent Applications No. CN02154432.8 claimsthe benefit of priority from Chinese Patent Applications No.CN02148379.5, filed on Nov. 12, 2002. All of the aforementioned patentapplications are hereby incorporated by reference in their entireties.

FIELD OF THE TECHNOLOGY

The present application relates to user information processing, and moreparticularly, to a method for processing a service connection between aWLAN (Wireless Local Area Network) and a user terminal.

BACKGROUND OF THE APPLICATION

As the requirement for the wireless access rate is becoming higher andhigher, the WLAN that can provide a higher wireless access rate within asmaller area has seen in fast development. Nowadays, there are manyavailable technologies for WLAN, one widely applied technical standardof which is IEEE 802.11b that uses the frequency band of 2.4 GHz;another alternative that uses the same frequency band is the Bluetooth.All other new technologies, such as IEEE 802.11a and ETSI BRANHiperlan2, use the frequency band of 5 GHz.

Although there are many different kinds of radio access technologies,most WLANs are used to bear IP (Internet Protocol) data packets. In awireless IP network, the WLAN access technology specific is usuallytransparent to the upper layer, e.g. IP layer or upper. All these IPnetworks are of the similar basic architecture which implements thewireless access of a user via the Access Point (AP) and builds an IPtransmission network through the connection of the network control andconnection devices.

Along with the springing up and development of the WLAN, how toimplement the interworking between the WLAN and various mobilecommunication networks, such as GSM, CDMA (Code-Division MultipleAccess) system, WCDMA (Wideband Code Division Multiple Access) system,TD-SCDMA (Time Division-Synchronize Code Division Multiple Access)system and CDMA2000 system, has become one of the highlights of currentresearch. In the scope of 3^(rd) Generation Partnership Project (3GPP)standard organization, simplified network architecture for interworkingbetween a WLAN system and a 3GPP system is shown in FIG. 1. A userterminal can communicate with not only the Internet and Intranet butalso the packet domain network of the 3GPP network via WLAN accessnetworks. It is obvious that, as a wireless access technology thatprovides IP bearer, the WLAN can be interconnected with many othernetworks.

Generally, while the WLAN connects with other networks, theauthentication, authorization and accounting operation for theconnection are controlled by an appropriate application server, forinstance, the AAA (Authentication, Authorization and Accounting) serverin a 3GPP system; and the subscriber information is managed by aninformation storage unit, for example, the HSS (Home Subscriber Server)or the HLR (Home Location Register) in the 3GPP system. Therefore, whenthe authentication, authorization and accounting processes is performed,the corresponding application server will request the user profile fromthe information storage unit, and store it temporarily in itself. Theapplication server will not release the information stored until theservice is terminated, wherein the so-called release refers to the stepthat the application server deletes the relevant data of the user who isnot access the service any more. In specific implementation, the datacan be deleted immediately after the user is offline, or be kept for acertain period of time before being deleted so that when the user logsin once again, the application server can use the stored data againwithout downloading it from the information storage unit. Once thesubscriber information in the information storage unit is changed, theinformation storage unit will notify the corresponding applicationserver to update the data.

In practice, there is no corresponding mechanism in the 3GPP standardsupporting the attach process by which a WLAN user requests to accessWLAN, i.e. the WLAN attach process. As a result, a WLAN user cannot knowwhether he/she has successfully accessed the WLAN, and whether he isable to use the services provided by the WLAN. In addition, the AAAserver cannot determine whether the WLAN based services are available tothe user. Similarly, there also is no corresponding mechanism in the3GPP standard supporting the detach process by which a WLAN user stopsusing the services and is detached from the WLAN, i.e. the WLAN detachprocess. Consequently, the WLAN user cannot make sure whether he hassuccessfully been detached from the WLAN, and furthermore, the AAAserver is also unable to determine whether the user is still able toenjoy the WLAN based services.

In addition, in order to prevent unnecessary signaling delivery, it isnecessary to synchronize the user information stored in the applicationserver and that in the information storage unit. For instance, inexisting specifications, when a user is attached or detached in a WLAN,the information about user connection can be updated only in the servicecontrol unit, i.e. the user information application server, such as theAAA server, without notification of the information storage unit for theuser, such as the HLR/HSS. The direct consequence of this mechanism isthat the information storage unit will not know the accurate statusinformation of the user, which makes the user information stored in theinformation storage unit unreliable. It is also possible that even afterthe user's disconnection from a WLAN, the information storage unitcontinues to ask for the user information, such as the serviceconnection status of the user and the user data, from the servicecontrol unit in subsequent processing, which results in unnecessarysignaling burden and meaningless system resource occupation. When thereis a large amount of such signaling, negative effects may be brought tothe normal operations of the system.

SUMMARY

In view of the above, it is the primary object of the presentapplication to provide a method for processing the user connectionbetween the WLAN and the user terminal, by which the WLAN and the userterminal can confirm the current service connection status of the WLANuser terminal, in order to achieve effective interactions and controlsbetween the WLAN user terminal and the service control unit.

Another object of the present application is to provide such a methodfor processing the service connection between the WLAN and the userterminal that can synchronize the user information stored in the userinformation storage unit and the user information in the service controlunit so as to avoid redundant message delivery and further improve theefficiency of the system.

In order to achieve the above objects, the present application isimplemented as follows:

A method for processing the user connection between the WLAN and theuser terminal is applicable to a WLAN consisting of a WLAN userterminal, a WLAN access unit, a service control unit and a userinformation storage unit, the method comprising:

Setting flags in the user terminal and the service control unit of aWLAN respectively, which represent the status of the connection betweenthe user terminal and the WLAN, e.g. attached or detached; establishingor canceling the connection between the user terminal and the WLAN bymeans of interaction between the WLAN user terminal and the WLAN, andmeanwhile modifying the corresponding flags.

Wherein, the service control unit may be a 3GPP AAA Server and the userinformation storage unit can be a HSS or a HLR.

The step of establishing the connection between the user terminal andthe network refers to attaching the WLAN user terminal to the WLAN,which further includes:

a11. when a WLAN user terminal accesses the WLAN, the WLAN user terminalsending an attach request message to the service control unit via theWLAN access unit;

a12. on receiving the attach request, the service control unit judgingwhether to allow the current WLAN user terminal to establish a serviceconnection, if not, the service control unit denying the attach requestsent by the user terminal and ending this procedure; otherwise, theservice control unit recording the service connection status of the WLANuser terminal as WLAN attached, then returning an access responsemessage to the WLAN user terminal.

Wherein, the attach request message in Step a11 contains a permanent ortemporary identification of the WLAN user terminal. On receiving theattach request, the service control unit first determines whether thepermanent or temporary identification of the user in the attach requestmessage is valid. If not, the service control unit initiates a requestprocedure to the user terminal to fetch a valid flag of the userterminal; otherwise, the service control unit determines whether havingstored in itself the user information of the user terminal that sent thecurrent request. If there is no such information, the service controlunit sends a request for the data information of the user terminal tothe corresponding user information storage unit; otherwise, goes to Stepa12 directly.

The determination on whether to allow the current WLAN user terminal toestablish the service connection in Step a12 is implemented by theexisting authentication procedure.

The method further includes: on receiving the access response messagesent by the service control unit, the WLAN user terminal modifying therelevant service connection flag in itself, indicating that the serviceconnection between the WLAN user terminal and the WLAN has beensuccessfully established.

The step of canceling the service connection between the user terminaland the network refers to detaching the WLAN user terminal from theWLAN, the process of which further includes: the WLAN user terminaldetaching from the WLAN, canceling the relevant service connection, andthe service control unit recording the service connection of the WLANuser terminal as WLAN detached. The detach procedure can be an ExplicitWLAN detach or an Implicit WLAN detach.

When the Explicit WLAN detach process is initiated by the WLAN userterminal, the method further comprises:

a21. the WLAN user terminal sending to the network a detach request thatcontains the reason that the WLAN user terminal is detached from theWLAN;

a22. on receiving the detach request, the service control unit recordingthe current service connection status of the WLAN user terminal as WLANdetached.

The detach process further comprises: the service control unit returninga response message to the WLAN user terminal, indicating that the WLANuser terminal has successfully been detached from the WLAN.

When the Explicit WLAN detach procedure is initiated by the WLAN, themethod further comprises:

The service control unit sending to the WLAN user terminal a detachrequest that contains the reasons that the WLAN user terminal isdetached from the WLAN; meanwhile, the service control unit recordingthe service connection status of the current WLAN user terminal as WLANdetached.

When the detach is an Implicit WLAN detach, the method furthercomprises: if there is no response from the WLAN user terminal after theWLAN initiates at least one contact operation with the WLAN userterminal, the service control unit directly recording the serviceconnection status of the WLAN user terminal as WLAN detached. Theprocess of Implicit WLAN detach further comprises: when the time duringwhich there is no contact between the relevant WLAN user terminal andthe WLAN exceeds a predetermined threshold, the WLAN initiating at leastone contact process to contact with the WLAN user terminal.

The flags set in the WLAN user terminal and the service control unit canbe new-defined specific flags or are implemented by re-using existingflags. The messages bearing the interactive procedures are implementedby new-defined specific messages or by re-using the messages in existingprocedures.

The attach or detach procedure mentioned above further includes: settinga flag that indicates the service connection status between the WLANuser terminal and the WLAN in the user information storage unit; theservice control unit sending a user-data updating instruction to theuser information storage unit, after recording the service connectionstatus of the current WLAN user terminal; the user information storageunit updating the service connection status of the current user terminalafter receiving the instruction, and then returning a user data updatingresponse to the service control unit after updating the user's serviceconnection information.

Therefore, when the current service connection status of a user ischanged to WLAN attached, the method further comprises:

c11. the service control unit setting the service connection status ofthe current WLAN user terminal as WLAN attached and simultaneouslysending an attach request to the user information storage unit;

c12. on receiving the attach request, the user information storage unitsetting the service connection status of the relevant WLAN user terminalas WLAN attached, and then returning a response message to the servicecontrol unit.

When the service connection status of a user is changed to WLANdetached, the method further comprises:

c21. the service control unit setting the service connection status ofthe current WLAN user terminal as WLAN detached, and simultaneouslysending a detach request to the user information storage unit;

c22. on receiving the detach request, the user information storage unitsets the service connection status of the relevant WLAN user terminal asWLAN detached, and then returning a response message to the servicecontrol unit.

When the user information is changed to WLAN detached, the method may aswell further comprises:

c31. the service control unit deleting the stored user data of thecurrent WLAN user terminal, and simultaneously sending a userinformation delete request to the user information storage unit;

c32. on receiving the delete request, the user information storage unitrecording that the user data of the current WLAN user terminal has beendeleted from the service control unit, and then returning a responsemessage to the service control unit.

Wherein deleting the user data in Step c31 comprises deleting theinformation of the WLAN user terminal from the service control unitimmediately after the WLAN user terminal disconnects from the WLAN; orkeeping, after the WLAN user terminal disconnects from the WLAN, theinformation of the WLAN user terminal in the service control unit for acertain period of time before deleting the information.

As described above, the method provided by this application forprocessing the service connection of a user in a WLAN clearly defines aWLAN attach procedure by which the WLAN user terminal accesses the WLANand a WLAN detach procedure by which the WLAN user terminal detachesfrom the WLAN so as to enable the service connection status (attach ordetach) of the WLAN user terminal to be controlled interactively andeffectively at the user terminal and the service control unit. Moreover,the method makes it possible to clearly indicate whether the currentuser terminal has successfully connected to the network and been able toenjoy the WLAN based services; or whether the current user terminal hassmoothly been detached from the WLAN and terminated the WLAN basedservices.

In addition, when the user accesses the WLAN or is detached from theWLAN, the user information storage unit or the service control unit willsend relevant messages each other in time so as to update simultaneouslythe user data in both the user information storage unit and the servicecontrol unit. Using the method of the present application can avoidredundant signaling burden and unnecessary occupation of the systemresource caused by the lost of synchronization of the user data, improvethe working efficiency of the system and the effectiveness of messagetransmission, and further provide more convenient and diversifiedservices for the WLAN user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified network architecture for the interworkingbetween the WLAN and 3GPP system;

FIG. 2 shows the system structure in the WLAN for processing changes ofthe service connection between the user and the WLAN;

FIG. 3 shows a flowchart for implementing the method in accordance withthe present application;

FIG. 4 shows a flowchart of the interactive procedure when a useraccesses the WLAN;

FIG. 5 shows a flowchart of the interactive procedure of the ExplicitWLAN detach initiated by a user terminal;

FIG. 6 shows a flowchart of the interactive procedure of the ExplicitWLAN detach initiated by the WLAN;

FIG. 7 shows a flowchart of the interactive procedure of the ImplicitWLAN detach initiated by the WLAN;

FIG. 8 shows an embodiment of the interactive operation between theservice control unit and the user information storage unit in a WLANdetach process according to the present application;

FIG. 9 shows another embodiment of the interactive operation between theservice control unit and the user information storage unit in a WLANdetach process according to the present application.

DETAILED DESCRIPTION

The present application will be described in detail hereinafter withreferences to the accompanying drawings and the preferred embodiments.

In view of the current WLAN technologies, the present applicationprovides an interactive method for various parts relating to theinformation of user service connection, such as the service control unitand the user information storage unit to process changes of the statusesof the WLAN user service connection when the connection is changed.There are two kinds of service connections statuses between the userterminal and the network, attached and detached. The presentapplication, by means of tracing the change in the service connectionbetween the WLAN user and the service control unit which takes placewhen the WLAN user accesses to or disconnects from the WLAN, provides amethod to enable both the user terminal and the WLAN to know whether theuser has successfully accessed the WLAN and the WLAN service isavailable or whether the user terminal has successfully beendisconnected from the WLAN and the WLAN service needs to be terminated.

The structure of the WLAN system implementing the above interactivemethod proposed by the present application is shown in FIG. 2,comprising: a WLAN user terminal 201, a WLAN access unit 202, a servicecontrol unit 203 and a user information storage unit 204. The WLANaccess unit 202 is responsible for the accessing and routing managementof the user terminal, enabling the user terminals therein to communicatewith each other using IP protocol and to connect and communicate withother IP networks. Generally speaking, the WLAN access unit mainlycomprises Access Points (AP) and Access Controllers (AC), and may alsocomprises routers for providing the network connectivity and relevantservers for network control. The service control unit 203, whichfunctions as a user control center in the WLAN system, controls theusers' access to the WLAN by means of authentication, and accounts forevery user terminal in the network. This service control unit can be asubscription information application unit. In practical applications,the AAA server is one example of the service control unit. The userinformation storage unit 204 is used for storing the information of allusers and can be implemented by the HSS/HLR.

The implementation process of the method in the present application isshown in FIG. 3, which comprises the steps of:

Presetting, respectively in the WLAN user terminal and the servicecontrol unit, flags that represent the attached or detached status ofthe service connection between the user terminal and WLAN. The flags canbe new-defined specific flags or can be implemented by re-using theflags that have already existed in the user terminal or the servicecontrol unit.

a. Perform the attach procedure when a service connection between theWLAN user terminal and the WLAN is to be established and set the flagsin the WLAN user terminal and the service control unit as WLAN attachedafter the WLAN user has successfully attached the WLAN.

b. Cancel the service connection between the user terminal and thenetwork through the interactions between the WLAN user terminal and theWLAN when the WLAN user terminal detaches from the WLAN andsimultaneously modify the relevant flags. It is also possible to modifythe flags of the service connection without the interactive procedure;for instance, when the wireless connection is interrupted resulting inthat the connection is unable to be established, the WLAN user terminalcan directly set the flag of the service connection as WLAN detached.

The causes for canceling the service connection between the WLAN userterminal and the network without notifying the network may also includean exceptional power off of the user terminal, a direct plug-off of theWLAN card from the computer, or a crashing down of the system, etc. Thenetwork will also set the flag of the service connection between theuser and the WLAN as WLAN detached after detecting that it is unable toconnect with the user terminal.

Take the AAA server as an example of the service control unit. When auser terminal accesses the WLAN, the AAA server determines whether thereis the user's information in itself. If there is no such information,the AAA server downloads the relevant user data from the userinformation storage unit (e.g. HSS/HLR) and stores it. After the userhas been successfully authenticated, the AAA server records the serviceconnection status between the current user and the WLAN as WLANattached, and at the same time sends a corresponding instruction to theuser, indicating that the user has already attached to the WLAN. Theuser terminal then indicates that the WLAN based services are availablethrough the proper change of the service connection or the correspondingflag.

The WLAN attach procedure of the user terminal is shown in FIG. 4. Inthis embodiment, the HSS/HLR acts as a user information storage unit.The procedure comprises the following steps:

Step 401: Establish a wireless connection between the user terminal andthe WLAN when the user needs to access the WLAN. After the wirelessconnection is successfully established, the WLAN user terminal sends aWLAN access request to the AAA server through the WLAN access unit. Therequest needs to identify clearly the type of network the user requeststo access is a WLAN and to contain a permanent or temporaryidentification of the user.

Step 402: On receiving the request, the AAA server determines if thereis a permanent or temporary identification in the access request messagesent from the user terminal. If not, the network needs to initiate arequest procedure to the user terminal to obtain the valididentification of the user terminal; otherwise, the AAA server continuesto determine whether there is in itself the user information of the userterminal that sends the request. If there is no such information in theAAA server, go to Step 403; otherwise, go to Step 405 directly.

Steps 403˜404: The AAA server sends a request to the relevant HLR/HSSfor the data of the user terminal; and the HLR/HSS sends the data ofuser terminal to the AAA server.

Step 405: The WLAN initiates an authentication procedure for the currentWLAN user terminal.

Step 406: After the authentication procedure completes successfully, theAAA server records the service connection between the user and the WLANas WLAN attached, and then go to Step 407; if the authenticationprocedure fails, the AAA server denies the access request of the userand ends the procedure.

Steps 407˜408: The AAA server sends a user data updating request to theHLR/HSS, and the HLR/HSS updates user status information of the currentWLAN user terminal; after the updating process, the HLR/HSS sends a dataupdating response message to the AAA server. This step can be optionalto avoid frequent updating of the user service connection statusinformation in the HLR/HSS.

Step 409: The AAA server returns an access response message to the WLANuser, indicating that the user has already been attached to the WLAN andthe WLAN is available. On receiving the message, the user terminal needsto modify the relevant flag, indicating that the WLAN service isavailable. For example, a flag of the WLAN service connection can be setand is switched to the active status at the moment.

The WLAN detach procedure of a user terminal falls into two groupsdepending on the detaching mode: Explicit WLAN detach and Implicit WLANdetach. The Explicit WLAN detach can be further divided into twosubgroups based on the initiator: the Explicit WLAN detach initiated bythe WLAN user terminal, and that initiated by the WLAN. In an ExplicitWLAN detach procedure initiated by a user terminal, the user terminalneeds to identify the reason for the detachment in the detach requestmessage sent to the WLAN; similarly, in an Explicit WLAN detachprocedure initiated by the WLAN, it is also necessary for the network toidentify the reason for the detachment in the detach request messagesent to the user. On the other hand, the Implicit WALN detach procedureis initiated by the network performed when the user has not contactedwith the WLAN for a long time. In this case, the network does not needto inform the user terminal after the detach procedure is completed.

Hereinafter is the detailed description on the above mentioned modes ofthe detach procedures:

1) When it is the WLAN user terminal that initiates a detach procedurefrom the WLAN, the user terminal informs the AAA server to terminate theWLAN service, and the service control unit, i.e. the AAA server, updatesthe corresponding service connection status to WLAN detached. As shownin FIG. 5, the procedure comprises the following steps:

Step 501: When a WLAN user terminal requests to detach from the WLAN,the WLAN user terminal sends a detach request to the network. Therequest message contains the reason for the detachment as well as thetype of the network the WLAN user terminal detaches from, i.e. WLAN.

Step 502: On receiving the detach request, the AAA server records theservice connection status of the user terminal as WLAN detached.

Step 503: The AAA server returns a response message to the current WLANuser terminal. This step is optional, the AAA server may decide based onthe actual situation whether or not to return to the user terminal theresponse message, indicating that the user has already detached from theWLAN. For instance, it may be only needed to set the corresponding flagsin the AAA server and the HLR/HSS in a WLAN detach procedure while notnecessary to inform the user terminal for the convenience of operationand maintenance. Moreover, the AAA server will change the serviceconnection status to WLAN detached when detecting there is no responsesent by the user terminal. At this time, the AAA server does not need tosend the notification to the user terminal, but simply sets the flag ofthe service connection status as WLAN detached.

2) It is possible for the WLAN to initiate a WLAN detach procedure for auser out of a reason from the network. In this case, the detachprocedure may be initiated by the AAA server or the HSS/HLR. In thisembodiment, the procedure is initiated by the AAA server, and the AAAserver updates the relevant service connection status of the currentuser terminal to WLAN detached. As shown in FIG. 6, the procedurecomprises the following steps:

Step 601: When the WLAN requests the WLAN user terminal to detach fromthe WLAN, the AAA server sends a detach request to the user terminal.The request message contains the type of the network to be detachedfrom, i.e. WLAN as well as the reason for the detachment.

Step 602: Simultaneously, the AAA server records the service connectionstatus of the WLAN user terminal as WLAN detached.

Step 603: The current WLAN user terminal returns a response message tothe AAA server, indicating the user has already detached from the WLANand the WLAN based service for the user has been terminated. This stepis optional. The user terminal may decide based on the actual situationwhether or not to return the response message to the AAA server.

3) Implicit WLAN detach procedure. When the user has not contacted withthe WLAN for a long time, a WLAN detach procedure will be initiated bythe AAA server. The AAA server will update the WLAN service connectionstatus of the user to WLAN detached, indicating that the WLAN service isno longer available to the user. In this case, the AAA server does notneed to send any notification to the user. As shown in FIG. 7, theprocedure comprises the following steps:

Steps 701˜702: After the AAA server has initiated a certain times ofcontacts with the WLAN user terminal, if there is still no response fromthe user terminal, the AAA server will directly record the serviceconnection status of the WLAN user terminal as WALN detached. The timesof contacts initiated by the AAA server before a detach procedure can beconfigured according to the actual situation. There are many reasonsthat the AAA server may initiate contacts with the user terminal: it maybe that the user has not contacted with the WLAN for a long time, thenrelevant timer in AAA server is expired, which may result in the AAAserver initiating the contact procedure with the user terminal. Otheruser applications may also request the AAA server to contact with theuser terminal.

In the Implicit and Explicit WLAN detach procedure mentioned above, inorder to guarantee that the data in the service control unit and in theuser information storage unit are consistent, the service control unitwill perform the detach procedures in two ways: (1) records the serviceconnection status of user as WLAN detached, sends a user detachnotification to the user information storage unit, and then the userinformation storage unit sets a corresponding flag for the currentservice connection status of the user; (2) directly deletes the userinformation without setting a flag for the service connection of theuser, sends a notification to the user information storage unitindicating that the user information has been deleted, and then the userinformation storage unit records that the user information has beendeleted in the service control unit.

The interactive process between the service control unit and the userinformation storage unit based on the method (1) is shown in FIG. 8,comprising the following steps:

Steps 801˜802: While performing the detach procedure, the AAA serversets the current service connection status of the user terminal as WLANdetached and sends a detach notification to the HSS/HLR simultaneously,indicating that the user has been detached from the WLAN;

Steps 803˜804: On receiving the notification, the HSS/HLR sets thecurrent service connection status of the relevant user terminal as WLANdetached, then returns a response message to the AAA server, indicatingthat the service connection status of the user has been correctlyupdated.

The interactive process between the service control unit and the userinformation storage unit based on the method (2) is shown in FIG. 9,comprising the following steps:

Steps 901˜902: While performing the detach procedure, the AAA serverdeletes the user data of the user terminal stored in itself and sends auser information delete notification to the HSS/HLR simultaneously,indicating that the data of the user terminal has been deleted in theAAA server;

Steps 903˜904: On receiving the notification, the HSS/HLR records thatthe user data of the corresponding WLAN user terminal has been deletedfrom the AAA server, then returns a response message to the AAA server,indicating that the HSS/HLR has set a flag indicating the user data hasbeen deleted.

In the attach or detach procedure mentioned above, it is also necessaryfor the user information storage unit to preset a flag representing theservice connection status between the WLAN user terminal and the WLAN.

The messages to support the above various interactive procedures can beimplemented by new-defined specific messages, for example, defined byMobile Application Part (MAP) protocol, Remote Authentication Dial inUser Service (RADIUS) protocol, or DIAMETER protocol. The interactiveprocedure can also be implemented by adding parameters to the existingmessages. The user information mentioned in the above solutions could bethe Subscription Information.

In summary, the above description is only preferable embodiments of thepresent application and is not to be construed as limits to theprotection scope of the present application.

1. A method for indicating a service connection status of a userterminal, comprising: setting, in a service control unit, a flagrepresenting either a Wireless Local Area Network (WLAN) attached statusor a WLAN detached status of the user terminal for a service connectionbetween the user terminal and the WLAN; and when the service connectionis changed from established to canceled or from canceled to established,modifying, by the service control unit, the flag corresponding to theservice connection status of the user terminal accordingly.
 2. Themethod according to claim 1, further comprising: a11. receiving, by theservice control unit, an attach request message from the user terminalvia a WLAN access unit; and a12. determining, by the service controlunit, whether to allow the user terminal to establish a serviceconnection with the WLAN; wherein when the service control unitdetermines not to allow the user terminal to establish a serviceconnection with the WLAN, the service control unit denies the attachrequest; and when the service control unit determines to allow the userterminal to establish a service connection with the WLAN, the servicecontrol unit records the service connection status of the user terminalas WLAN attached, and returns an access response message to the userterminal.
 3. The method according to claim 2, wherein the attach requestmessage in Step a11 comprises a permanent or temporary identification ofthe user terminal; on receiving the attach request, the service controlunit first determines whether the permanent or temporary identificationof the user terminal in the attach request message is valid; if thepermanent or temporary identification of the user terminal is not valid,the service control unit initiates a request procedure to the userterminal to fetch a valid flag of the user terminal; if the permanent ortemporary identification of the user terminal is valid, the servicecontrol unit determines whether itself has stored the user informationof the user terminal; if there is no user information of the userterminal in the service control unit, the service control unit sends arequest for the data information of the user terminal to a userinformation storage unit.
 4. The method according to claim 2, whereinthe determining, by the service control unit, whether to allow the userterminal to establish the service connection comprises: determining, bythe service control unit whether to allow the user terminal to establishthe service connection in an authentication procedure.
 5. The methodaccording to claim 2, further comprising: upon receiving the accessresponse sent by the service control unit, modifying, by the userterminal, a flag stored in the user terminal to indicate that theservice connection between the user terminal and the WLAN has beensuccessfully established.
 6. The method according to claim 2, furthercomprising: setting in a user information storage unit a correspondingflag that indicates the service connection status of the user terminal;recording, by the service control unit, the service connection status ofthe WLAN user terminal; sending, by the service control unit, a userdata updating instruction to the user information storage unit;updating, by the user information storage unit, the corresponding flagthat indicates the service connection status of the user terminal onreceiving the user data updating instruction, and returning, by the userinformation storage unit, a user data updating response to the servicecontrol unit.
 7. The method according to claim 6, wherein when theservice connection status of the user terminal is changed from WLANdetached to WLAN attached, the method further comprises: c11. setting,by the service control unit, the service connection status of the userterminal as WLAN attached and sending an attach notification to the userinformation storage unit; and c12. setting, by the user informationstorage unit, the service connection status of the user terminal as WLANattached, and returning a response message to the service control unit.8. The method according to claim 6, wherein when the service connectionstatus of the user terminal is changed from WLAN attached to WLANdetached, the method further comprises: c21. setting, by the servicecontrol unit, the service connection status of the user terminal as WLANdetached, and sending a detach notification to the user informationstorage unit; and c22. setting, by the user information storage unit,the service connection status of the user terminal as WLAN detached, andreturning a response message to the service control unit.
 9. The methodaccording to claim 6, wherein when the service connection status of theuser terminal is changed from WLAN attached to WLAN detached, the methodfurther comprises: c31. deleting, by the service control unit, user dataof the current WLAN user terminal stored in the service control unit,and sending a user information delete notification to the userinformation storage unit; and c32. recording, by the user informationstorage unit, the user data of the user terminal that has been deletedfrom the service control unit, and returning a response message to theservice control unit.
 10. The method according to claim 9, wherein thedeleting, by the service control unit, user data of the current WLANuser terminal stored in the service control unit comprises: deletinginformation of the user terminal from the service control unitimmediately after the user terminal is disconnected from the WLAN. 11.The method according to claim 9, wherein the deleting, by the servicecontrol unit, user data of the current WLAN user terminal stored in theservice control unit comprises: keeping, after the user terminal isdisconnected from the WLAN, information of the WLAN user terminal in theservice control unit for a certain period of time before deleting theinformation.
 12. The method according to claim 1, wherein canceling theservice connection between the user terminal and the WLAN comprisesdetaching the user terminal from the WLAN, and wherein the detaching theuser terminal from the WLAN further comprises: the user terminaldetaching from the WLAN, canceling the service connection, and theservice control unit recording the service connection of the userterminal as WLAN detached; and wherein the detaching the user terminalfrom the WLAN is an Explicit WLAN detaching or an Implicit WLANdetaching.
 13. The method according to claim 12, wherein if the ExplicitWLAN detach is initiated by the user terminal, the method furthercomprises: a21. the user terminal sending to the WLAN a detach requestthat includes at least one reason why the user terminal detaches fromthe WLAN; and a22. the service control unit recording the serviceconnection status of the user terminal as WLAN detached.
 14. The methodaccording to claim 13, further comprising: the service control unitreturning a response message to the user terminal, indicating the userterminal has been detached from the WLAN.
 15. The method according toclaim 12, wherein if the Explicit WLAN detaching is initiated by theWLAN, the method further comprises: the service control unit sending adetach request that includes at least one reason why the user terminalis detached from the WLAN; and the service control unit recording theservice connection status of the user terminal as WLAN detached.
 16. Themethod according to claim 12, wherein if the detaching the user terminalfrom the WLAN includes the Implicit WLAN detach, the method furthercomprises: if there is no response from the user terminal after the WLANinitiates at least one contact attempt to the user terminal, the servicecontrol unit recording the service connection status of the userterminal as WLAN detached.
 17. The method according to claim 16, furthercomprising: If a time period during which there is no contact betweenthe user terminal and the WLAN exceeds a predetermined duration, theWLAN initiating at least one contact operation to contact the userterminal.
 18. The method according to claim 12, further comprising:setting in the user information storage unit a third flag that indicatesthe service connection status between the user terminal and the WLAN;the service control unit recording the service connection status of theuser terminal and then sending a user data updating instruction to theuser information storage unit; the user information storage unitupdating the service connection status of the user terminal on receivingthe user data updating instruction, and then returning a user dataupdating response to the service control unit.
 19. The method accordingto claim 18, wherein when the service connection status of the userterminal is changed to WLAN attached, the method further comprises: c11.the service control unit setting the service connection status of theuser terminal as WLAN attached and simultaneously sending an attachnotification to the user information storage unit; and c12. the userinformation storage unit setting the service connection status of theuser terminal as WLAN attached, then returning a response message to theservice control unit.
 20. The method according to claim 18, wherein whenthe service connection status of the user terminal is changed to WLANdetached, the method further comprises: c21. the service control unitsetting the service connection status of the user terminal as WLANdetached and sending a detach notification to the user informationstorage unit; and c22. the user information storage unit setting theservice connection status of the user terminal as WLAN detached, andthen returning a response message to the service control unit.